Ultramarine blue is a deep blue pigment that has been an historically rare and costly pigment. In its natural form, the blue is made from ground lapis lazuli, which is a unique stone found in very few parts of the world. The pigment can, however, be crafted synthetically. The chemical compound that makes up ultramarine blue consists mainly of a double silicate of sodium and aluminum.
The name ultramarine derives from the Latin ultramarinus. In Middle Latin, ultra means beyond, and marinus means the sea. Therefore, the word means, from beyond the sea. The term probably came about because the pigment was originally imported to Europe from Asia, by way of the historic Silk Road and the Mediterranean Sea.
Natural ultramarine blue pigment comes from the mineral lazurite, which is one of the main components of lapis lazuli. This is a deep blue stone that often has pyrite or calcite veins running through it. The stone was originally mined in what is now known as the Badakhshan province of Afghanistan. Other deposits have been located and mined in areas around the world, but the stone remains rare.
The synthetic pigment for ultramarine blue is typically created by baking clay, sulfur, charcoal, and special chemical compounds containing sodium, carbon, and silicon together in a kiln. Sometimes the chemicals are altered to create different colors, such as ultramarine violet. The baked solids are ground and washed to create a usable pigment.
This blue has been used in paints and glazes for thousands of years. Before it was produced synthetically, ultramarine blue was very costly to manufacture and was therefore rarely used. During the Middle Ages, manuscript illuminators typically saved the color for pages with scenes of great religious significance.
The synthetic pigment has been used in both oil and water-based paints. The chemical compound in ultramarine blue is stable and non-toxic, so it is typically safe for human contact. That property is the main reason it is often used in the manufacture of cosmetics, food packaging, and toy production. It also has excellent heat, light, and weather resistance properties, so it can have many outdoor uses as well, such as in exterior paint.
Ultramarine blue pigment is often used as a color corrective for white paper. Adding a little bit of the pigment to normal paper pulp, along with an optical whitening agent, will often offset the natural yellow of paper pulp. This process actually makes the finished paper a crisper, cleaner white color.